Overview
The Honeywell S87C Direct Spark Ignition control module is a solid-state, low-voltage controller designed to manage direct spark ignition systems in gas-fired furnaces, boilers, and heating appliances. This module delivers proven reliability for HVAC and refrigeration applications requiring dependable ignition sequencing and flame monitoring. The S87C provides electronic control of ignition timing, gas valve operation, and burner flame detection in commercial and industrial heating systems.
Key Features
- High-Voltage Spark Generation: 30,000 V open circuit spark generator voltage ensures consistent spark ignition across all operating conditions.
- Dual-Electrode System: S87C uses a separate flame sensor distinct from the igniter, enabling precise flame detection and ignition control.
- Safety Lockout: Generates high voltage potential for main burner ignition and lockout after one trial for ignition if main burner fails to ignite.
- Flexible Installation: Mounts in any position for adaptable system design.
- Compact Connector Design: Snap-spring connectors, 1/4 in. (6.4 mm) diameter for reliable quick-connect installation.
- Wide Operating Range: Ambient temperature rating of -40°F to 175°F (-40°C to 79°C) supports diverse HVAC environments.
Technical Specifications
- Electrical Supply: 25 Vac, 60 Hz
- Control Current Rating: 0.2 A at 25 Vac
- Valve Contact Rating: 2.0 A at 25 Vac for S87C model
- Spark Igniter Voltage: 30,000 V open circuit
- Flame Failure Response: 0.8 seconds maximum
- Flame Current Signal Required: 1.5 DC minimum microamps
- Safety Lockout Timing: 4, 6, 11, 21 seconds (nominal) selectable trial times
- Ignition Cable: Maximum length 3 ft (0.9 m)
- Relative Humidity Rating: 5 to 95 percent at 90°F (32°C)
- Wiring Terminals: 1/4 in. male quick-connect terminals for system connections, 3/16 in. male quick-connect terminal for alarm, and 1/4 in. diameter stud base for ignition cable
- Internal Protection: 3A fuse
- Listing: UL File No. MH11790
Typical Applications
- Gas-fired forced-air furnace ignition control
- Commercial and residential boiler ignition sequencing
- Industrial heating appliance flame management
- HVAC system direct spark ignition retrofit and replacement
- Dual-electrode burner systems requiring separate spark igniter and flame sensor
- Low-voltage thermostat control integration for heating cycles
Compatibility & Replacements
Compatible With
- Honeywell gas controls designed for DSI application: V845, V854, VR845, VR854, VR8450, VR8540
- Gas-fired furnaces and boilers with direct spark ignition burners
- 24 Vac thermostat control systems
- DSI-rated gas valves rated 2.0 A maximum
- Recommended flame sensors per manufacturer specification table
Replaces / Drop-In Replacement For
- S87C can be used for direct field replacement of S825A and S825C models
- Previous-generation Honeywell DSI control modules in equivalent applications
Works With
- Honeywell flame sensors (Q354A, Q342)
- Honeywell spark igniters (Q347A, Q330)
- Standard 24 Vac HVAC control transformers
- Low-voltage thermostat switching circuits (0.2 A + valve draw)
- Direct spark ignition burner assemblies with separate igniter and flame sensor electrodes
